Recycling of waste PET, either post-consumer or non-post-consumer, is a worldwide concern due to its environmental impact and the increasing volume of these materials being produced by society.
Furthermore, energy curable coating compositions and inks, in particular, ultraviolet (UV) curable coating compositions and inks have become increasingly popular because they do not employ volatile organic solvents and thus avoid the associated health and environmental concerns. Furthermore they are applicable in a wide range of printing techniques and cure rapidly upon irradiation.
Curing of energy curable coating compositions and inks predominantly proceeds via a radical polymerization mechanism. Thus, the binder/resin material of the coating compositions and inks advantageously must comprise functional groups which are capable of undergoing radical polymerization. Typically, these functional groups are unsaturated groups such as acrylate groups.
U.S. Pat. No. 6,127,436 is directed to a method of depolymerizing reclaimed, recycled or virgin PET via an alcoholysis reaction using glycols and polyhydric alcohols. The depolymerizied product is then esterified with polybasic carboxylic acids, anhydrides or acyl halides to produce a composition containing inert oligomeric binders which are useful in curable coatings.
David E. Nikles, Medhat S. Farahat—Macromol. Mater. Eng. 2005, 290, 13-30—New Motivation for the Depolymerization Products Derived from Poly(Ethylene Terephthalate) (PET) Waste: a Review; discloses that PET waste can be converted to acrylate-terminated PET low molecular weight oligomers by a two-stage process, first glycolysis with diethylene glycol followed by reaction with acryloyl chloride which can be cured by UV radiation.
Consequently it is an object of the present invention to provide a polyester acrylate resin which is derived from substantial amounts of reclaimed, recycled or virgin PE, that is advantageously highly energy curable and has a sufficiently high molecular weight such that it can be suitably incorporated into coating compositions or inks.